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It's too early to panic, but we should seriously start wondering whether the bombs found on airplanes in Dubai and Britain are signs of a new, more dangerous wave of terrorism. Homeland Security Secretary Janet Napolitano described the bombs as having "all the hallmarks of al-Qaeda." But the more ominous truth is that these bombs have the hallmark of a higher degree of professionalism than we've ever seen come out of al-Qaeda. If al-Qaeda indeed made them, they've teamed up with true professionals.

PETN, the explosive found in these two bombs, is the preferred explosive of professional bombmakers. It's particularly lethal, but more importantly it's malleable and can be disguised as all kinds of things. In the '80s, a Palestinian bombmaker "rolled" PETN and hid it in the lining of Samsonite suitcases. One of his bombs nearly brought down an American airliner. Hizballah disguised PETN as olives, painted them black and transported them in highly leaded glass, which defeated then advanced airport X-rays. Finally, last year a Yemeni group attempted to kill the Saudi intelligence chief by secreting PETN in a body cavity. The intelligence chief was wounded but survived. (See the top 10 inept terrorist plots.)

There have been various unconfirmed intelligence reports that some of these accomplished bombmakers, including the man who hid PETN in Samsonite suitcases, have sneaked into Yemen and are now allied with groups that claim allegiance to al-Qaeda. They're helping make bombs for the Yemeni militants and teaching them to make them themselves.

Something else that should worry us about Yemen is that the militants there appear to have better intelligence and organization than al-Qaeda has shown in the past. Had the Yemeni suicide bomber managed to kill the Saudi intelligence chief, Prince Mohammed bin Nayef, it would have been a disaster for Saudi Arabia as well as the U.S. The intelligence chief is the man credited with turning back al-Qaeda in Saudi Arabia, arresting most of the major networks and convincing Saudi Arabia's hard-line clerics to stop supporting Osama bin Laden's jihad. For those pessimists (like me) who thought Saudi Arabia would never defeat its militants, this man pulled off nothing short of a miracle. His would-be assassins knew exactly who to go after. (See TIME's story "Terror Plot Foiled: But Is the Threat in Yemen Growing?")

Finally, we should also wonder whether the field of battle has shifted from under our feet. Has al-Qaeda fled the tribal areas of Pakistan and taken refuge in the mountains of Yemen? A lot of people have speculated this, and it would make good sense. After al-Qaeda started attacking Pakistani government targets after 9/11, Pakistan has slowly cracked down on the organization to the point that it's almost impossible for Arab and other international jihadists to make their way across Pakistan to the tribal areas, al-Qaeda's rear base. And with NATO forces on the ground in Afghanistan, al-Qaeda's oxygen has all but been cut off. Like any guerilla organization under siege, it moved. (See a special report on the accused 9/11 plotters.)

If indeed al-Qaeda's base is now in Yemen, we're facing a whole new dynamic. Yemen's well-armed and notoriously independent tribes are even less likely than those of Pakistan to stand for a sustained aerial campaign against the militants. Angered, the tribes can be all but counted on to move on Yemen's capital Sana'a and other major cities, dragging the country into a full-fledged civil war. Or they will increase their attacks on America's ally, Saudi Arabia.

If this is an accurate assessment of what's happened  the battlefront has moved to Yemen  the Obama Administration had better start boning up on Yemeni tribal politics.

Baer, a former Middle East CIA field officer, is TIME.com's intelligence columnist and the author of See No Evil and, most recently, The Devil We Know: Dealing with the New Iranian Superpower.